Manufacture of shells



UNITED STATES ROBERT ABBOTT HADFIELD, OF WESTMINSTER, ENGLAND.

MANUFACTURE OF SHELLS.

Specification of Letters Iatent.

Patented Nov. 2. 1920 No Drawing. Application filed August 10, 1917, Serial No. 185,522. Renewed September 17, 1920. Serial No. 410,963.

To all whom it may concern Be it known that I, Sir ROBERT Anm'r'r HADFIELD, Baronet, F. R. 8., a subject of the King of Great Britain and Ireland, residing at city of lVestminster, En land, have invented Improvements in or elating to the Manufacture of Shells, of which the following is a specification.

As is well understood, it is very important that shells intended to contain high ex plosive should'be aslittle liable as possible to crack, break, or set up while being fired from a gun.

Now this invention has for object to produce shells, particularly of large caliber, and especially suitable for use as high explosive shells, that shall be of a more reliable quality and better adapted for the purpose mentioned than the high explosive shells heretofore used.

For this purpose .a shell designed to contain a high explosive is composed of untempered and unhardened nickel chromium steel that has been heat treated and has an elastic limit of the order of from about 23 to 30 tons to the square inch, a'tensile strength of the order of from about 42 to 54 tons to thesquare inch and an elongation of the order of from about 15 to 30% with a reduction of area at the break of the order of from about 34 to 58%.

Such a high explosive shell is produced according to this invention by forging or pressing a nickel chromium steel ingot or blank to shape and afterward heat treating it by placing it in a cold furnace, then slowly heating the furnace up to a temperature of from about 750 to 800 C. so that it attains this temperature after several hours, then maintaining such temperature for several hours and then allowing the furnace to cool down slowly for several hours.

The nickel chromium steel may advantageously contain from about decimal four five to decimal six of one per cent. of carbon and about two per cent. each of nickel and chromium, silicon being say about decimal two to decimal four of one per cent..and manganese say about decimal two to decimal eight of one per cent, according to the mechanical qualities desired.

By way of example it may be stated that a fifteen inch nickel chromium steel shell forged or pressed approximately to shape with a thick metal base and having about the following composition, viz., carbon about 47%, nickel about 2%, chromium about 195% silicon about .19%, manganese about 27%, sulfur about 036% and phosphorus about 028%, was, after being machined roughly to the finished shape, heat treated by first placing it in a cold furnace and slowly heating the furnace up to a temperature of about 765 C. in twenty six hours, then maintaining the shell at that temperaturefor about twenty six hours and afterward allowing it to cool down in the furnace to about ordinary temperature in about twenty four hours. The steel composing this heat treated shell, as determined from test pieces taken from different parts thereof, was found to have an elastic limit varying from about 231} tons to the square inch at the solid base to about 27 to 29 tons at the open front end; a tensile strength of from about 46 tons to the square inch at the base end and about 42 tons per square inch at the front end; and'elongation of from about 17.5% at the base end to about 24 to 25.5% at the front end and a reduction in area at the fracture of the test pieces of from about 34%. at the base end to about 40 to 49% at different parts of the front end. The steel had a. hardness, as determined by the Brinell ball test of from about 166 to 177.

After the heat treatment, a, shell made according to the invention may desirably be finished to the required shape and dimensions ready to be charged with high explosive and fitted with a fuse, without being subjected at any stage, to any tempering or hardening treatment. Instead of heat treating the shell after being forged or pressed roughly to shape, the steel blank from which it is made may be heat treated as described, or both the blank and the shell made therefrom, may be heat treated as described. As will be understood a shell improved in its characteristics by the treatment as described may if desirable afterward be hardened and tempered.

What I claim is 1. The process of manufacturing an untempered and unhardened nickel chromium steel shell designed to contain high explosive and having a high elastic limit. a high tensile strength and high elongation as set forth. said process consisting in slowly heating such shell during several hours up,

:then allowing it to cool down slowly for 1 several hours.

2. The process of manufacturing an untempered and unhardened nickel chromium steel shell designed to contain a high explosive and having a high elasticlimit, a high tensile strength and high elongationas set forth, said process consisting in slowly heating the shell to a temperature of about 750 to 800 (3., maintaining it at about that temperature for a considerable period and allowing it to cool down very slowly.

3. The process of manufacturing an unhardened and untempered shell having a high elastic limit, a high tensile strength and high elongation as set forth which consists in heating a nickel chromium steelshell containing from about decimal .four

five to decimal six of one per cent. of car- Icon and about two per cent. each of nickel and chromium slowly for several hours to a high temperature, maintaining it at that I temperature for several hours and then allowing it to cool slowly during several hours. i

4. The process of manufacturing ad unhardened and unteinpered shell having a high elastic limit, a high tensile strength and high elongation as set forth, which consists in heating a nickel chromium steel shell composed of steel containing from about decimal four five to decimal'six of one per cent. of carbon and about two per cent. each of nickel and chromium slowly during a period of several hours up to a temperature of from about 7 50 to 800 (1., maintaining it at that temperature for several hours and allowing it to cool slowly during several hours.

5. The process of manufacturing a shell having a high elastic limit, a .high tensile strength and high elongation as set forth and designed to contain high explosive, which consists in converting a nickel chromium steel ingot or blank containing from about decimal four five to decimal six of one per cent. of carbon and about two per cent. each of nickel and chromium, into a shell, then slowly heating theshell from the cold to a temperature of from about 750 to 800 C. so that it attains this tempera-- ture'after several hours, then maintaining it at such temperature for several hoursand then allowing it to cool down slowly for several hours, and then finishing the shell to the required shape anddimensions nickel chromium steel ingot or blank con taining about decimal four five to decimal six of one per cent. of carbon and about two per cent. each of nickel and chromium and low in silicon, manganese, sulfur and phosphorus as set forth, into a shell, then slowly heating the shell up to a temperature of'about 765 C. in about twenty six hours, maintaining it at this temperature for about twenty six hours and allowing it to cool down slowly to about ordinary temperature in about twenty four hours, and then finishing the shellto the required shape and dimensions ready to be charged with high explosive and fitted. with a fuse, without subjecting it at any stage of its manufacture to any tempering or hardening treatment.

7. The process of manufacturing shells of nickel chromium steel to produce a shell having a high elastic limit, high tensile up to a high temperature, maintaining it at the high temperature for approximately twenty-six hours and then allowing it to cool down slowly over a period of approximately twenty-four hours, substantially as described.

8. The process of manufacturing nickel chromium steel shell having a high elastic limit, a high tensile strength and high elongation as set forth which consists in subjecting said shell in an untempered and unhardened, state to heat treatment consisting in slowly heating the shell to a temperature of about 750 to 800 (1., maintaining it about that temperature for a considerable period and allowing it to cool down very slowly.

9. The process of manufacturing shell having a high elastic limit, high tensile strength and high elongation which con- ROBERT ABBOTT HADFIELD.

Witnesses: v

. WILLIAM CROSS,

LEONARD Row r 

